1. Technical Field
The present invention relates to a semiconductor sensor and a method for manufacturing the semiconductor sensor.
2. Related Art
Recently, chemical sensors, odor sensors, gas sensors, and the like that detect chemical substances in the air have been developed in response to increasing awareness of environmental issues. In the sensors, a sensitive film on which chemical substances adsorb is formed on a piezoelectric element, such as a quartz crystal resonator and a surface acoustic wave element, and the mass change of the sensitive film corresponds to the oscillation frequency change of the piezoelectric element. As a result, the chemical substances can be detected by using the mass change.
For example, JP-A-2007-147556 discloses a method for manufacturing a thin film (sensitive film) and a chemical sensor using the thin film manufactured by the method. In order to improve adsorption sensitivity (i.e., the sensitivity of the sensor), the method includes: a step for mixing a sensitive film material and fine particles; a step for forming a thin film with a mixture of the sensitive film material and the fine particles; a step for drying the thin film; and a step for removing the fine particles exposed at the thin film surface after being dried, thereby increasing the adsorption area of the thin film.
The related art described above has a problem in that such particular steps are additionally required in order to improve the adsorption sensitivity of the sensitive film, increasing the manufacturing costs and the price of the chemical sensor.